SAHARAN WIND REGIMES TRACED BY THE Sr–Nd ISOTOPIC COMPOSITION OF SUBTROPICAL ATLANTIC SEDIMENTS: LAST GLACIAL MAXIMUM vs TODAY

Grousset, F.; Parra, M.; Bory, A.; Martinez, Philippe; Bertrand, Pierre; Shimmield, Graham; Ellam, Robert M.

doi:10.1016/s0277-3791(97)00048-6

Cited by 223 publications

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“…For instance, a warming in the Mediterranean Sea basin could favour the northward expansion of the monsoon in summer (Rowell, 2003;Hall and Peyrillé, 2006). Saharan dust particles are fine silts and clay-size minerals (Grousset et al, 1998;Grousset and Biscaye, 2005;Stuut et al, 2009) and the grain-size distribution of this material showed mean sizes below 6 µm ( Fig. 3d) (RodrigoGámiz et al, 2011), in this study we investigated the fine silt fraction, i.e.…”

Section: Radiogenic Isotopes As Proxies For Unravelling Chemical Weatmentioning

confidence: 99%

“…Radiogenic isotopes (Sr, Nd, Pb) are likewise powerful tracers for identifying and characterizing source areas of terrigenous material, which may in turn give us additional information about the provenance and transport mechanisms (e.g., Grousset et al, , 1992Grousset et al, , 1998Revel et al, 1996;Tütken et al, 2002;Grousset and Biscaye, 2005;Jullien et al, 2007;Cole et al, 2009;Box et al, 2011;Meyer et al, 2011;Stumpf et al, 2011;Scheuvens et al, 2013).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

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Radiogenic isotopes for deciphering terrigenous input provenance in the western Mediterranean

et al. 2015

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Section: Radiogenic Isotopes As Proxies For Unravelling Chemical Weatmentioning

confidence: 99%

Section: Accepted M Manuscriptmentioning

confidence: 99%

Radiogenic isotopes for deciphering terrigenous input provenance in the western Mediterranean

et al. 2015

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“…(D) Nd concentration of river runoff (in ng/g) Goldstein and Jacobsen (1987); scale is non linear. (E) Interpolated ε Nd map of atmospheric dust (Grousset et al, 1988;Grousset et al, 1998;Jeandel et al, 2007). Dust particle fields are provided by Tegen and Fung (1995), and Nd concentration is set constant to 20 µg/g.…”

Section: Description Of Nd Sources and Sinkmentioning

confidence: 99%

“…Atmospheric dust flux is determined using monthly maps provided by Tegen and Fung (1995), in agreement with the method used for the PISCES model for nutrients . Nd IC of this source has been established using available data (Grousset et al, 1988(Grousset et al, , 1998. However, in the areas where no data were available, the ε Nd of the dust is determined according to the ε Nd value for the region of origin of the dusts (Fig.…”

Section: Description Of Nd Sources and Sinkmentioning

confidence: 99%

Reconstructing the Nd oceanic cycle using a coupled dynamical – biogeochemical model

et al. 2009

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Abstract. The decoupled behaviour observed between Nd isotopic composition (Nd IC, also referred as ε Nd ) and Nd concentration cycles has led to the notion of a "Nd paradox". While ε Nd behaves in a quasi-conservative way in the open ocean, leading to its broad use as a water-mass tracer, Nd concentration displays vertical profiles that increase with depth, together with a deep-water enrichment along the global thermohaline circulation. This non-conservative behaviour is typical of nutrients affected by scavenging in surface waters and remineralisation at depth. In addition, recent studies suggest the only way to reconcile both concentration and Nd IC oceanic budgets, is to invoke a "Boundary Exchange" process (BE, defined as the co-occurrence of transfer of elements from the margin to the sea with removal of elements from the sea by Boundary Scavenging) as a source-sink term. However, these studies do not simulate the input/output fluxes of Nd to the ocean, and therefore prevents from crucial information that limits our understanding of Nd decoupling. To investigate this paradox on a global scale, this study uses for the first time a fully prognostic coupled dynamical/biogeochemical model with an explicit representation of Nd sources and sinks to simulate the Nd oceanic cycle. Sources considered include dissolved river fluxes, atmospheric dusts and margin sediment re-dissolution. Sinks are scavenging by settling particles. This model simulates the global features of the Nd oceanic cycle well, and produces a realistic distribution of Nd concentration (correct order of magnitude, increase with depth and along the conveyor belt, 65% of the simulated values fit in the ±10 pmol/kg envelop when compared to the data)Correspondence to: T. Arsouze (arsouze@ldeo.columbia.edu) and isotopic composition (inter-basin gradient, characterization of the main water-masses, more than 70% of the simulated values fit in the ±3 ε Nd envelop when compared to the data), though a slight overestimation of Nd concentrations in the deep Pacific Ocean may reveal an underestimation of the particle fields by the biogeochemical model. Our results indicate 1) vertical cycling (scavenging/remineralisation) is absolutely necessary to simulate both concentration and ε Nd , and 2) BE is the dominant Nd source to the ocean. The estimated BE flux (1.1×10 10 g(Nd)/yr) is much higher than both dissolved river discharge (2.6×10 8 g(Nd)/yr) and atmospheric inputs (1.0×10 8 g(Nd)/yr) that both play negligible role in the water column but are necessary to reconcile Nd IC in surface and subsurface waters. This leads to a new calculated residence time of 360 yrs for Nd in the ocean. The BE flux requires the dissolution of 3 to 5% of the annual flux of continental weathering deposited via the solid river discharge to the continental margin.

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“…The coherent and predictable behavior of REEs, along with their sensitivity to pH, redox conditions and their tendency to participate in adsorption/ desorption reactions, allows them to be used as input provenance markers, meteorization processes or geochemical tracers of changes in environmental conditions in water and sediments (Sholkovitz, 1992;Ǻstrom, 2001). REEs are useful for interpretation of diagenetic redox conditions in palaeoenvironmnental research (Shields and Stille, 2001), monitoring detrital sediment sources (Grousset et al, 1998), and elucidating seawater circulation patterns (Tachikawa et al, 1999), hydrothermal fluxes (German et al, 1999), and the historic oxygenation of the oceans (Henderson, 1984;Murray et al, 1992). They are also important tools for identifying anthropogenic effects on intertidal sediment, especially those caused by unnatural liquid or solid inputs which modify the geochemical characteristics of the sediment (Borrego et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Rare earth elements in intertidal sediments of Bohai Bay, China: Concentration, fractionation and the influence of sediment texture

Zhang

Gao

Chen

2014

Ecotoxicology and Environmental Safety

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a b s t r a c tSurface sediments from intertidal Bohai Bay were assessed using a four-step sequential extraction procedure to determine their concentrations of rare earth elements (REEs) and the chemical forms in which those elements were present. The normalized ratios La/Gd and La/Yb showed that LREE contents were not significantly higher than the middle REEs or HREE contents. A negative Ce anomaly and positive Eu were observed in sand and silty sand sediments, whereas no significant Ce or Eu anomaly was found in clayey silt sediments. Residual fraction of REEs accounted for the majority of their total concentrations. Middle REEs were more easily leached than other REEs, especially in clayey silt sediment. REEs contents in the surface sediment from the intertidal Bohai Sea were consistent with data from the upper continental crust and China shallow sea sediments, indicating that they were generally unaffected by heavily anthropogenic effects from adjacent areas.

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SAHARAN WIND REGIMES TRACED BY THE Sr–Nd ISOTOPIC COMPOSITION OF SUBTROPICAL ATLANTIC SEDIMENTS: LAST GLACIAL MAXIMUM vs TODAY

Cited by 223 publications

References 0 publications

Radiogenic isotopes for deciphering terrigenous input provenance in the western Mediterranean

Radiogenic isotopes for deciphering terrigenous input provenance in the western Mediterranean

Reconstructing the Nd oceanic cycle using a coupled dynamical – biogeochemical model

Rare earth elements in intertidal sediments of Bohai Bay, China: Concentration, fractionation and the influence of sediment texture

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